Scroll machinery for fluid compression or expansion is typically comprised of two upstanding interfitting involute spirodal wraps or scrolls which are generated about respective axes. Each respective scroll is mounted upon an end plate and has a tip disposed in contact or near contact with the end plate of the other respective scroll. Each scroll further has flank surfaces which adjoin, in moving line contact or near contact, the flank surfaces of the other respective scroll to form a plurality of moving chambers. Depending upon the relative orbital motion of the scrolls, the chambers move from the radially exterior ends of the scrolls to the radially interior ends of the scrolls for fluid compression, or from the radially interior ends of the scrolls to the radially exterior ends of the scrolls for fluid expansion. The scrolls, to accomplish the formation of the chambers, are put in relative orbital motion by a drive mechanism. Either one of the scrolls may orbit or both may rotate eccentrically with respect to one another.
A typical scroll machine, according to the design which has a non-orbiting scroll, includes an orbiting scroll which meshes with the non-orbiting scroll, a thrust bearing to take the axial loads on the orbiting scroll and a motion controlling member for preventing relative rotation of the scroll members. The motion controlling member preferred for preventing relative rotation of the scroll members is usually an Oldham coupling.
In the marketplace, there is an increasing demand for much quieter machinery than was hitherto acceptable, and this is especially true for air conditioning and heat pump systems. In the case of refrigerant compressors used for air conditioning and heat pump applications, sound has become an increasingly important criteria for judging acceptability. There are a number of identified sources of sound in a scroll compressor, many of which are relatively easily cured. A recently discovered source of sound which does not lend itself to easy cure, however, concerns the mechanical impact noise or rattle which is caused by vibration of the motion controlling member in relation to various components of the compressor under certain operating conditions. These operating conditions include when the compressor is operating under lighter load conditions when there is insufficient loading of the compressor components including the motion controlling member to prevent force reversals which can cause the motion controlling member to impact noisily on the components of the compressor with which it interfaces and conditions when the motion controlling member wobbles within the compressor as a result of the interaction between the drive loads, gas forces, thrust bearings or other components of the compressor.
Accordingly, it would be desirable to insure that there is sufficient loading of the motion controlling member in all directions and at all operating conditions of the compressor to prevent the force reversals and the wobbling of the motion control member and thus eliminate the mechanical impact or rattle which is caused by the vibration of the motion controlling member.
It is therefore a primary objective of the present invention to provide means for biasing the motion controlling member in order to take up the normal build and operating clearances that are present in the scroll machinery which can contribute to the mechanical impact or rattle caused by the vibration of the motion controlling member.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.